The present invention relates generally to an aqueous dispersion of a vinylidene chloride resin. More particularly, the present invention relates to an aqueous dispersion of a vinylidene chloride resin which has good adhesive properties and which is capable of forming a coating having a good printability. The coating also has an excellence in gas (especially oxygen) and water vapor barrier properties and in resistance to boiling water treatment.
Polypropylene, polyester, nylon or like plastic films show markedly improved barrier properties to gas and water vapor if coated with, either directly or through the medium of one or more anchor coats, an aqueous dispersion of a vinylidene chloride resin. Therefore, aqueous vinylidene chloride resin dispersions are valuably utilized as coatings for such plastic films.
The aqueous vinylidene chloride resin dispersions of the present invention must be capable of forming coatings which have good adhesive properties to substrate films and printability (i.e. their fitness for securing good adhesion of printing ink thereto). Said coatings must also have good laminatability to other films. A topmost requisite for such aqueous vinylidene chloride resin dispersions is a capability to form a coating having excellent barrier properties with respect to gas and water vapor.
Many foods or like products are now stored or sold as packed in vinylidene chloride resin-coated film bags. Some foods may require sterilization through boiling after being packed. Coated films which are subjected to sterilization must have a high resistance to a boiling water treatment. In other words, such coated films must undergo neither clarity loss nor reduction in gas barrier properties as a result of the boiling water treatment, while maintaining their excellence in the other aforementioned properties.
Accordingly, the present invention provides an improved aqueous vinylidene chloride resin dispersion which can generally satisfy the aforementioned requirements.